Deficiencies of vitamins A and E may adversely affect both the outcome of pregnancy and the health of premature infants, in whom repeated serum measurements are problematic. Both vitamins exhibit potent antioxidant activity in vitro, and breath ethane (a volatile product of lipid peroxidation) is a useful index of vitamin E deficiency. The purpose of this project is to examine the utility of breath ethane as a noninvasive functional biomarker for these two deficiencies in pregnant women and their infants. PART I. MOTHER-INFANT PAIRS (18 months). In 90 mothers, at 28 weeks gestation, breath ethane will be correlated with serum vitamin A (SVA), retinol-binding protein (RBP), serum vitamin E (SVE), and SVE:total lipids. The effects of the following on breath ethane will be assessed: intake of vitamins A and E and iron (a major pro-oxidant), anthropometrics, smoking, alcohol, illness, and other serum antioxidants (Zn, Cu, Mn, Se, carotene and vitamin C). Correlation of breath ethane with another measure of lipid peroxidation, (plasma malondialdehyde) will be done. Infant breath ethane obtained 24-48 hours postpartum will be correlated with infant SVA, RBP and SVE, and with maternal breath ethane at 28 weeks. Since our obstetric population consists of inner-city mothers with marginal diets, this group should represent a spectrum of vitamin A and E nutriture and is thus ideal for this project. PART II. PREMATURE INFANTS (18 months). The lowest weight and earliest gestational age at which breath ethane can be reliably used to reflect vitamin A and E status will be determined as will the best means of measuring breath ethane in mechanically ventilated infants. The effects of postpartum age (Group 1) and normalization of vitamin A and/or E status (Group 2) on breath ethane in infants <37 weeks gestation, will be assessed. Initial SVA and SVE, and Group 2, 40 infants with subnormal initial SVA and/or SVE; follow-up SVA and SVE will be obtained weekly in each group x3 weeks. Sufficient supplemental vitamin A and/or E will be given orally or, if required, intramuscularly to normalize SVA and SVE. THis test can be an excellent means of monitoring response to therapy, particularly in small infants.